Sewer laying system

ABSTRACT

The sewer laying system comprises a tile setting apparatus which rides along the bottom of a ditchline and lays compacted layers of aggregate material under and over tiled sections, and which provides mechanical force for setting sections of tile into the pipeline.

United States Patent 1191 Brown Sept. 23, 1975 1 SEWER LAYING SYSTEM2,738,745 3/1956 Harpold 61/72.l 3,290,804 12/1966 6l/72.l X [76] Inventf' Bmwn, BOX 3,421,609 1/1969 Schmunk 193 2 Kmgston, ldahO 838393,820,345 6/1974 Brecht 61/72.l x [22] Filed: Oct. 9, 1973 PrimaryExaminer-Jacob Shapiro [211 App! 404847 Attorney, Agent, or Firm-John W.Kraft; Charles L.

Kraft, II [52] US. Cl. 61/72.5; 61/41 A; 214/1 PA;

214/17; 404/106 57 B TRACT [51] Int. Cl. E02F 5/10 1 A S [58] Field ofSearch 61/72.1, 72.2, 72.5, 72.7, The Sewer laying System comprlses asettmg pp 61/41 A; 404/106, 101; 214/1 PA, 17, 185 PH ratus which ridesalong the bottom of a ditchline and lays compacted layers of aggregatematerial under and 5 References Cited over tiled sections, and whichprovides mechanical UNITED STATES PATENTS force for setting sections oftile into the pipeline. 2,656,800 10/1953 Reising 61/72.1 18 Claims, 13Drawing Figures US Patent Sept. 23,1975 Sheet10f6 3,906,737 I US PatentSept. 23,1975 Sheet 2 of6 3,906,737

US Patent Sept. 23,1975 Sheet 3 of6 3,906,737

US Patent Scpt. 23,1975 Sheet 4 of6 3,906,737

US Patent Sept. 23,1975 Sheet 5 of6 3,06,737

FIG. M)

Era? 2: il-F FIG. 1111 US Patent Sept. 23,1975 Sheet 6 of6 3,906,737

FIG. 13

SEWER LAYING SYSTEM FIELD OF THE INVENTION The present invention relatesto apparatus for laying subterranean pipelines, and, more particularly,to apparatus for mechanically laying tile, which may propel itself alonga ditchline.

DESCRIPTION OF THE PRIOR ART Laying of tile for subterranean sewers andpipelines and the like may be conveniently divided into a tile settingfunction, and a tile and aggregate feeding function. The tile settingfunction entails placing a base layer of aggregate material whichsupports the tile, feeding and setting the tile into the ditchline, andplacing a cover layer of aggregate material over the top to hold anddrain the tile. This process has been accomplished by a variety ofapparatus having variously configured housings which usually includesolid walls of the ditchline, having means for laying aggregate materialadjacent the tile, and having various aggregate feeding means, tilehoists, lifts and chutes, and the like. It is typical of the prior artthat the apparatus be propelled by lifting or dragging the housing alongthe ditchline. Further, it is an apparent convention that the housing ofthe tile laying apparatus be fabricated of rigid walls which necessitatethe removal of the entire apparatus from the ditchline when encounteringpipelines, telephone and power cables, and similar obstructions, or thetemporary disconnection of utility lines. Thus, it may be seen that tilelaying apparatus of the prior art required large capacity liftingapparatus to be operable.

A tile laying apparatus of the prior art has provided a multiplicity ofaggregate feeding means which merely lay aggregate in place. It isbroadly recognized that this loose, uncompacted aggregate laid in asmooth line will necessarily settle in an even repose. It is a furtherelement of the prior art that some back force may be applied to the tileas it is set. High-back force on the en- -tire line is seldomappliedpthus, joints aligned during the initial tile-setting steps maybecome loosened, or not fully engaged, as the pipeline progresses. Somewell received tile laying apparatus of the prior art have attempted tomitigate these problems by laying a base layer of aggregate-likecurvature in which the pipe may rest. This solution assumes that thelower apex of the concave arc of the aggregate is in alignment with theideal centerline of the pipeline; this is seldom true. It should benoted that guidance of pipe laying apparatus characteristically omittedany integrated guidance and alignment indicating meansgalignment hasconventially .been accomplished by a simple transom shot over the top ofthe pipeline housing.

Accordingly, it is an object of the present invention to provide anapparatus for laying subterranean pipelines having a tile settingapparatus and a closely associ- 'ated tile and aggregate feedingapparatus.

It is a further primary object of this invention to provide aself-propelled tile setting apparatus.

It is an object of this invention that the aforesaid tile settingapparatus be provided with means for laying a compacted base layer ofaggregate material, and a suitable top layer. I

It is an object of this invention to provide the aforesaid tile settingapparatus with means for applying back force on tile and pipeline.

It is' another object of this invention to provide aforesaid tilesetting apparatus with telescoping side walls to permit passage of theapparatus under pipelines, utility cables and the like.

It is an object of the present invention to provide aforesaid tilesetting apparatus with an integrated fundamentally accurate guidance andalignment indicating apparatus.

It is an object of this invention to provide the aforesaid tile andfeeding apparatus with integrated frame works and prime movers formoving tile and aggregate.

These and other objects shall become apparent from the descriptionfollowing, it being understood that modifications may be made withoutaffecting the teachings of the invention here set out.

SUMMARY OF THE INVENTION The sewer laying system comprises a tilesetting apparatus which rides along the bottom of a ditchline and layscompacted layers of aggregate material under and over tiled sections,and which provides mechanical force for setting sections of tile intothe pipeline. The tile setting apparatus comprises a chassis trestle, atilebed laying car which runs on the top rails of the chassis trestle,and a cover car which also rides on the top rails of the chassis trestlebehind the tile-bed laying car. The tile setting apparatus may beactuated forwardly along the ditchline by forcing the tile-bed layingcar against the ditchline to force the trestle forwardly.

A more thorough and comprehensive understanding may be had from thedetailed description of the preferred embodiment when read in connectionwith the drawings forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a right front perspectiveview of the sewer laying system of this invention including the tilesetting apparatus and the tile carrying and service unit.

FIG. 2 is a right side elevational view of the apparatus of FIG. 1.

FIG. 3 is a right front perspective view of the tile setting apparatus.

FIG. 4 is a fragmentary right side elevational view of the lead tile-bedlaying car of this invention shown on a trestle broken away forillustrative purposes.

FIG. 5 is a front end elevational view of the lead car takensubstantially from the line 55 of the FIG. 4.

FIG. 6 is a perspective view o'fa section of a top rail of the trestle,and of a typical car wheel shown with the car wheel in its respectiveoperating positions in solid and broken lines for illustrativepurposes.

FIG. 7 is a front end elevational view of the backfill car of thisinvention, shown; in an environment with subsoil, tile, and aggregates.

FIG. 8 is a side elevational view of the apparatus of the FIG. 7, shownwith a portion of its side wall broken away for illustrative purposes.

FIG. 9 is a left side elevational view of the tile setting apparatusshown with the cars in the first phase of operation.

FIG. 10 is a left side elevational view of the apparatus in the FIG. 9shown with its left trestle wall removed and a compact layer ofaggregate material laid by the bed laying car, and with a section oftile installed waiting to be covered with aggregate by the backfill car.

FIG. 1 1 is a left side elevational view of the apparatus of the FIG.shown with a layer of compacted backfill laid over the new section oftile.

FIG. 12 is a fragmentary perspective view of the backfill laying carshowing the tamper thereof.

FIG. 13 is a schematic diagram of the hydraulic system of the tilesetting apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawings and more particularly to the FIGS. 1 and 2, the sewer layingsystem of this invention comprises a tile setting apparatus and a tilecarrying and service unit, generally identified by the numerals 10 and11 respectively. The present sewer laying system is intended to handletiles 12 and fill material by means of the tile carrying and serviceunit 11 and to set tiles 12 and backfill aggregate material by means ofthe tile setting apparatus 10. As shall become more clear hereinafter,the tile setting apparatus 10 and the tile carrying and service unit 1 1may be used as separate apparatus in their further respective purposes.

As shown in the FIG. 3, the tile setting apparatus 10 comprises achassis trestle 13, a tile-bed laying car 14, and a cover fill car 15.The trestle 13 comprises a pair of parallelly disposed base rails 16 and16', a pair of parallelly disposed top rails 17 and 17' disposedparallelly over the base rails 16 and 16' respectively, and amultiplicity of suitable pillars 18 and diagonals 19 supporting the toprails 17 and 17' over the respective base rails 16 and 16'. The baserails 16 and 16 may be fabricated of rolled section or box girders. Thebase rails 16 and 16 provide skids upon which the trestle 13 may restand move. The top rails 17 and 17', which shall be described at lengthhereinafter, carry cars 14 and and are fabricated in an interiorlydisposed C-shaped configuration against which the cars 14 and 15 mayact. Transverse beams 20 connect the terminal ends of the base rails 16and 16' and the top rails 17 and 17' respectively. The forwardmostterminal end of the trestle 13 is provided with upwardly curved,boat-like nose 21 which may minimize or eliminate bulldoze effects ofthe forward motion of the trestle 13 over the ground, hereinafter laterdescribed.

The tile-bed laying car 14 is the forward car of the cars 14 and 15 inthe trestle 13. It is intended to apply a layer of compacted aggregatematerial on which the tiles 12 may rest. Referring to the FIGS. 3, 4,and 5, the tile-bed laying car 14 includes a chute-hopper 22, which isopen at the top and bottom, having a pair of substantially upstandingside walls 23 and 23, and a pair of end walls 24 and 24 which areinclined away from the transverse centerline of the car 14. Thechutehopper 22 is distally narrower than the interior distance betweenthe top rails 17 and 17 of the trestle 13, and rides on the top rails 17and 17 on trolleys 25, as shown more clearly in the FIG. 6. The trolleys25 are mounted at the forward and rearward ends of the chute-hopper 22,each of which rides within the top rails 17 and 17. The trolley wheels25 are provided on transversely disposed shafts 25". The circumferentialedge of each of the trolley wheels 25' is provided with centrallydisposed gear teeth 26 and rims 27 and 27' at each side of the teeth 26.Thus, it may be seen that the teeth 26 are substantially flush orrecessed with respect to the rims 27 and 27'. The top rails 17 and 17'have a substantially upstanding C-shaped configuration with the openingsthereof disposed centrally with respect to the rectilinear central lineof the trestle 13. The interior sides of the upper and lower walls ofthe top rails 17 and 17 are provided with racks 28 and 28' respectively.The vertical distance between the upper and lower racks 28 and 28' isdistally greater than the outer diameter of the wheels 25'. The forwardtrolley shaft 25" is driven by a prime mover, such as a hydraulic motor29 mounted to the forward side of the car 14. The motor 29 may bemechanically connected to the shaft 25" by a gear box 30 in a mannerwhich becomes more clear hereinafter. In operation, the car 14 may bedriven with respect to the rails 17 and 17 by engaging the wheels 25'with either appropriate rack 28 or 28', and activating the motor 29. Itis to be understood that, although a single motor 29 has been described,a pair of motors may be employed on each shaft 25", and thecorresponding idling shaft may be provided with smooth wheels.

The bottom of the car 14 is open, and the end walls 24 and 24 areprovided with spreading means distally narrower than the distancebetween the base rails 16 and 16. The opening of the bottom of the car14 is operable to release a predetermined flow of aggregate; and, thus,when taken with the usual speed of the car 14 moving with respect to thetrestle 13, the car 14 provides a predetermined thickness of compactedaggregate material at the bottom of the ditchline. The'rearward wall 24is provided with a reciprocating tamper 31. The tamper 31 issubstantially coextensive in width with the wall 24', and ridesfrictionlesslymithin tracks 31 fastened to the vertical edges of thewall 24'. The tamper 31 may be reciprocated with respect to the wall 24by any of a variety of mechanical means, such as an hydraulic motor 32connected to the tamper 31 by an eccentric linkage 33. The reciprocatingtamper 31 is operable to compact material issuing from the bottom of thechute-hopper 22 as the car 14 progresses with respect to the trestle 13.

The capacity of the chute-hopper 22 may be increased by providingtelescoping walls 34. The telescoping walls 34 may comprise a variety ofnestling segments 35. Each segment 35 comprises a polygonal enclosure ofupstanding metal strips. The upper terminal edge of each segment 35 isprovided with lips (not shown) which interlock with each respectivesegment 35 above and below, with the lowest segment 35 fastened to theuppermost edge of the chute-hopper 22. The walls 34 may be lowered andextended by a hydraulic cylinder 36 which is pivotally mounted betweenthe uppermost terminal end of the hopper-chute 22 and the uppermostterminal end of the telescoping walls 34. In operation, when the car 14encounters an obstacle which could collide with the telescoping walls34, the hydraulic cylinder 36 may be permitted to contract to collapsethe telescopic walls 34. When the car 14 progresses past the obstacle,the hydraulic cylinder 36 may be extended to extend the walls 34. It maybe seen that the walls 34 permit the car 14 or the trestle 13 to bemoved through a ditchline having obstacles without necessarily removingthe tile setting apparatus 10.

The car 14 includes a tile setting bumper 38 by which compressive forcemay be applied to the bell flange portion 12' of a tile 12 beinginstalled in a pipeline. The bumper 38 comprises a rearwardly projectingsideframe 39 issuing from the lower and upper rearward terminal side ofthe chute-hopper 22, at'the rearward end wall 24, and a push-ring 40.The sideframe 39 may include a suitably stressed structure consisting ofa lower beam 41 fastened to the lowermost terminal end of the rearwardwall 24' of the chute-hopper 22, a but tress of stringers 42 whichprovide a box-like support structure for the lower beam 41," andcrossties 43' and diagonals 44 to provide structural strength. Thepushring 40 is an upstandingly disposed member which may be fabricatedas a wall to contact the terminal "end of the bell flange 12', or as amember operable to both contact the terminal end and engage the bellflange 12'. In operation, the motor 29 may be used to drive the car 14in a rearward direction with respect to the trestle 13, and theresultant force thus'provided may be transmitted through the bumper 38to the tile 12. It may be seen that the force applied by'the bumper 38would almost necessarily be in alignment with the pipeline, thusproviding better engaged tiles 12.

Referring again to the FIG. 3,the rear cover car 15 is operable to coverthe tile 12 with a compacted layer of aggregate material. As shownin'FIGS. 7 and 8, the car 15 is fabricated similarly to the car 14. Theca'r 15 includes a chute-hopper 45 including upstanding side walls 46and 46' and forward and rearward incline walls 47 and 47; and is open atthe uppermost terminal ends in the same fashion as the chute-hopper 22.The car 15 also includes telescoping walls 48 similar to the walls 34,controlled by a hydraulic cylinder 49. The car 15 is also provided withtrolleys 52, comprising geared wheels 51 on a transverse shaft 52'driven by a motor 53 in the manner of the trolleys 25 set out above.

As shown more clearly in the FIG. 12, the cover car 15 is also providedwith a reciprocating tamper 54. The tamper 54 is actuated in africtionless track 55 by a prime mover, such as an hydraulic motor 56mounted to the rearward side of the chute-hopper 45 and connected to thetamper 54 by a pivotally, eccentrically mounted linkage 57. As shown inthe FIG. 7, the lowermost terminal edge of the tamper 54 is providedwith a centrally disposed curve recess 54' which permits the lower edgeof the tamper 54 to follow the intended curvature of the tile 12 coveredwith aggregate. The lowermost terminal edge of the end walls 47 and 47of the chute-hopper 45 is provided with a curved recess to apply auniform layer over the upper curvature of the compacted,aggregate-covered, tile 12.

Referring again to the FIGS. 3 and 13, each side of the forwardmost endof the trestle 13 is provided with a pair of substantially upstandingcylinders 58 having weight-distributing pads 59 at the lowermostterminal ends of the respective pistons and valve means 58.. Thetile-bed laying car 14 is provided distally from each side of theforwardmost end wall 24 with upstanding cylinders 60. Each of thecylinders 60 is provided with weight-distributing pads 60 on thelowermost end of the pistons, and valve means 60". The car 14 having asuitably powerful motor 29 may be used alone to actuate the trestle 13.It may be seen that the car 14 operates through the central balanceregion of the trestle 13 to carry and distribute the weight of theapparatus during relocation along the ditchline. Each side of therearward, cover-fill car may be provided with upstanding cylinders 61having pads 61 at the lowermost terminal ends of the pistons, andcontrol valves 61". The cylinders 61 of the car 15 may provide furtherweight support. The cylinders 61 may also be projected from the car 15at a suitable angle to provide means for applying resultant force if thecar 15 is used to drive a trestle 13 along the ditchline as shall bedescribed hereinafter.

As shown more clearly in the FIG. 13, any of a number of types of primemovers to be employed in the tile setting apparatus 10 may be selected,including a hydraulic system connected to a common source which shallhereinafter be described. Accordingly, the prime movers may be providedwith closed conduit connections singularly or in several combinations,and may be provided with valve means of the type set out above. It mayalso be seen that equivalent prime movers may include'electric motorsand winch and cable rigged connections.

Referring to the FIGS. 9, l0, and 11, the mode of operation of the tilesetting apparatus 10 is shown to advantage. As shown in the FIG. 9, cars14 and 15 are filled with a suitable aggregate material; and arepositioned at the rearwardmost terminal end of the trestle 13. It may beseen that the cover car 15 has covered the pipeline to a point distallyfrom its forwardmost terminal end with a layer of compacted aggregatematerial. As shown in the FIG. 10, the forward, bed laying car 14 ismoved forwardly with respect to the trestle 13, and lays a suitablelayer of compacted aggregate material as set out above. Sections of thetile 12 may be laid within the trestle in the pipeline and may beengaged by the means of 'the bumper 38 as set out above. As shown in theFIG. '11, the cover car 15 may then cover the newly added tiles 12 witha layer of compacted aggregate material, as set out above, to a pointdistally from the new forward terminal end of the pipeline. Theoperation for moving the trestle 13 forwardly along the ditchline may beaccomplished by first extending the hydraulic cylinders and 61 to retainthe cars 14 and 15 in a stationary position. The motors 29 and 53 may beactivated in a reverse direction of rotation engaging the drive trolleys25 with the upper racks 28 of the top rails 17 and l7 to drive thetrestle 13 forwardly with respect to the cars 14 and 15 in alignmentwith the pipeline, as indicated by the arrow in the FIG. 11. The cars 14and 15 are then found at the rearward portion of the trestle 13, and maybe filled with aggregate materials to repeat the tile laying process.The hydraulic cylinders 58 may be used to partially raise the trestle 13to reduce friction between the bottom rails 16 and 16 and the bottom of.the ditchline.

It may be seen that course corrections of the trestle 13 for bothdirection and grade may be effected by selective activation of thecylinders 58, 60 and/or 61. Changes in direction may be made byextending one or more of the cylinders 58, 60 or 61 on one rectilinearside of the trestle 13 more than cylinders 58, 60 or 61 on the sideopposite. In practice it has been found to advantage to control theforwardmost cylinders 58 by separate valves (not shown), therebycontrolling the nose 21 with respect to the remainder of the trestle 13.Changes in grade may be made by extending the transversely pairedcylinders 58, 60 and 61 to change the depth of aggregate material laidwith respect to the bottom of the ditchline. Again, it may be seen thatthe forwardmost pair of cylinders 58 may provide the most sensitive andresponsive guide means.

Any of a number of means may be used to guide and control the alignmentof the trestle 13 on a pipeline course. One suggested means is to directa surface beam of light, such as a laser beam, through the interior ofthe pipeline from the rearward end of the pipeline with respect to thetrestle 13 to a detector device (not shown) at the push-ring 40 of thebumper 38. One detector means may be to use a photoelectric detectormounted in the push-ring 40. The detector may be connected toservomechanisms for controlling the hydraulic cylinders 58, 60 and 61;or be connected to indicator means to which the cylinders 58, 60 and 61may be controlled manually.

Having thus described in detail a preferred apparatus which embodies theconcepts and principles of the invention and which accomplishes thevarious objects, purposes and aims thereof, it is to be appreciated andwill be apparent to those skilled in the art that many physical changescould be made in the apparatus without altering the inventive conceptsand principles embodied therein. Hence, it is intended that the scope ofthe invention be limited only to the extend indicated in the appendedclaims.

I claim:

1. A tile setting apparatus, comprising:

a chassis trestle including a pair of parallelly disposed base rails, apair of top rails disposed on pillars parallelly above and insubstantial alignment with said base rails, and transverse beamsconnecting respective terminal ends of said base and top rails;

a tile-bed laying car mounted between said top rails of said trestle ontrolleys, one of said trolleys being provided with means for motivatingsaid car along said top rail, said car having side walls and end wallsforming an enclosure which is open at the top and bottom to collect andpass a predetermined layer of aggregate material and a tile settingbumper projecting rearwardly from said car and having a push ring havingmeans for engaging a bell flange of a tile; and

a cover fill car being mounted rearwardly of said bed laying car withinsaid trestle on said trolleys, one of said trolleys having means formotivating said cover car along said top rails, said cover car havingside walls and end walls forming an enclosure which is open at its topand bottom to collect and release a predetermined layer of covermaterial over installed tiles.

2. The apparatus of claim 1 wherein said top rails have an upstandingC-shaped configuration with their openings disposed centrally withrespect to said trestle, and wherein said trolleys include wheels whichmay ride within said top rails.

3. The apparatus of claim 2 wherein the interior side of the upperportion of said C-shaped top rails includes a rack, and wherein saidtrolley wheels include gear teeth which mesh with said rack.

4. The apparatus of claim 2 wherein the interior side of the lowerportion of said C-shaped top rails includes a rack, and wherein saidtrolley wheels include gear teeth which mesh with said rack.

5. The apparatus of claim 3 wherein the circumference of said trolleywheels includes rims disposed at each side of said gear teeth to makeflush or recess said gear teeth.

' 6. The apparatus of claim 2 wherein the interiormost vertical distanceof said upstanding, C-shaped, top rails is distally greater than thediameter of said trolley wheels.

7. The apparatus of claim 1 wherein each side of said tile-bed layingcar includes a pressure cylinder having a piston which is extensibleinto the bottom of a ditchline to raise said car with respect to saidtop rail, said cylinders being controlled by suitable valve means.

8. The apparatus of claim 1 including a pressure cylinder mounted ateach side distally from the forwardmost terminal end of said trestle,said cylinders being controlled by suitable valve means.

9. The apparatus of claim 1 wherein each side of said cover fill car isprovided with a pressure cylinder having a piston which may extend intothe ground and raise said car with respect to said top rail, saidcylinders being controlled by suitable valve means.

10. The apparatus of claim 1 wherein the uppermost terminal edge of saidside walls of said bed laying car is provided with extensibletelescoping walls.

11. The apparatus of claim 10 wherein said telescoping walls areextended by a pressure cylinder fastened between the uppermosttelescoping wall section and said side wall portion of said bed layingcar.

12. The apparatus of claim 1 wherein the uppermost terminal edge of saidside walls of said cover car is pro vided with telescoping walls.

13. The apparatus of claim 12 wherein said telescoping walls areextended by a pressure cylinder fastened between the uppermosttelescoping wall sections and said side wall portion of cover car.

14. The apparatus of claim 1 wherein the rearwardmost terminal side ofsaid bed laying car is provided with a reciprocating tamper.

15. The apparatus of claim 14 wherein said tamper rides in frictionlesstracks and is reciprocated by a motor connected to said tamper by aneccentric linkage.

16. The apparatus of claim 1 wherein said rearwardmost terminal side ofsaid cover fill car is provided with a reciprocating tamper.

17. The apparatus of claim 16 wherein said tamper rides in frictionlesstracts and is reciprocated by a motor connected to said tamper by aneccentric linkage, the lowermost terminal edge of said tamper isprovided with a centrally disposed recess which follows a predeterminedcurvature of compacted aggregate material over said tile.

18. The apparatus of claim 1 including an upwardly curved, boat-likenose issuing forwardly from the forwardmost terminal end of saidtrestle.

1. A tile setting apparatus, comprising: a chassis trestle including apair of parallelly disposed base rails, a pair of top rails disposed onpillars parallelly above and in substantial alignment with said baserails, and transverse beams connecting respective terminal ends of saidbase and top rails; a tile-bed laying car mounted between said top railsof said trestle on trolleys, one of said trolleys being provided withmeans for motivating said car along said top rail, said car having sidewalls and end walls forming an enclosure which is open at the top andbottom to collect and pass a predetermined layer of aggregate materialand a tile setting bumper projecting rearwardly from said car and havinga push ring having means for engaging a bell flange of a tile; and acover fill car being mounted rearwardly of said bed laying car withinsaid trestle on said trolleys, one of said trolleys having means formotivating said cover car along said top rails, said cover car havingside walls and end walls forming an enclosure which is open at its topand bottom to collect and release a predetermined layer of covermaterial over installed tiles.
 2. The apparatus of claim 1 wherein saidtop rails have an upstanding C-shaped configuration with their openingsdisposed centrally with respect to said trestle, and wherein saidtrolleys include wheels which may ride within said top rails.
 3. Theapparatus of claim 2 wherein the interior side of the upper portion ofsaid C-shaped top rails includes a rack, and wherein said trolley wheelsinclude gear teeth which mesh with said rack.
 4. The apparatus of claim2 wherein the interior side of the lower portion of said C-shaped toprails includes a rack, and wherein said trolley wheels include gearteeth which mesh with said rack.
 5. The apparatus of claim 3 wherein thecircumference of said trolley wheels includes rims disposed at each sideof said gear teeth to make flush or recess said gear teeth.
 6. Theapparatus of claim 2 wherein the interiormost vertical distance of saidupstanding, C-shaped, top rails is distally greater than the diameter ofsaid trolley wheels.
 7. The apparatus of claim 1 wherein each side ofsaid tile-bed laying car includes a pressure cylinder having a pistonwhich is extensible into the bottom of a ditchline to raise said carwith respect to said top rail, said cylinders being controlled bysuitable valve means.
 8. The apparatus of claim 1 including a pressurecylinder mounted at each side distally from the forwardmost terminal endof said trestle, said cylinders being controlled by suitable valvemeans.
 9. The apparatus of claim 1 wherein each side of said cover fillcar is provided with a pressure cylinder having a piston which mayextend into the ground and raise said car with respect to said top rail,said cylinders being controlled by suitable valve means.
 10. Theapparatus of claim 1 wherein the uppermost terminal edge of said sidewalls of said bed laying car is provided with extensible telescopingwalls.
 11. The apparatus of claim 10 wherein said telescoping walls areextended by a pressure cylinder fastened between the uppermosttelescoping wall section and said side wall portion of said bed layingcar.
 12. The apparatus of claim 1 wherein the uppermost terminal edge ofsaid side walls of said cover car is provided with telescoping walls.13. The apparatus of claim 12 wherein said telescoping walls areextended by a pressure cylinder fastened between the uppermosttelescoping wall sections and said side wall portion of cover car. 14.The apparatus of claim 1 wherein the rearwardmost terminal side of saidbed laying car is provided with a reciprocating tamper.
 15. Theapparatus of claim 14 wherein said tamper rides in frictionless tracksand is reciprocated by a motor connected to said tamper by an eccentriclinkage.
 16. The apparatus of claim 1 wherein said rearwardmost terminalside of said cover fill car is provided with a reciprocating tamper. 17.The apparatus of claim 16 wherein said tamper rides in frictionlesstracts and is reciprocated by a motor connected to said tamper by aneccentric linkage, the lowermost terminal edge of said tamper isprovided with a centrally disposed recess which follows a predeterminedcurvature of compacted aggregate material over said tile.
 18. Theapparatus of claim 1 including an upwardly curved, boat-like noseissuing forwardly from the forwardmost terminal end of said trestle.